U.S. patent application number 14/620197 was filed with the patent office on 2016-07-14 for cover film with high dimensional stability and manufacturing method of flexible printed circuit board.
The applicant listed for this patent is Taiflex Scientific Co., Ltd.. Invention is credited to Wen-Chien Chen, Wei-Yuan Huang, Chi-Sheng Hung, Wu-Ying Su, Meng-Cheng Tsai, Hsiu-Chu Wu, Ching-Wen Yu.
Application Number | 20160205776 14/620197 |
Document ID | / |
Family ID | 56368523 |
Filed Date | 2016-07-14 |
United States Patent
Application |
20160205776 |
Kind Code |
A1 |
Wu; Hsiu-Chu ; et
al. |
July 14, 2016 |
COVER FILM WITH HIGH DIMENSIONAL STABILITY AND MANUFACTURING METHOD
OF FLEXIBLE PRINTED CIRCUIT BOARD
Abstract
A cover film with high dimensional stability includes an
insulation film, a first adhesive layer, and a carrier. A first
side of the first adhesive layer is connected to a first surface of
the insulation film, and a second side of the first adhesive layer
is configured to adhere to at least one metal conductor of a
flexible printed circuit board. The carrier includes a supporting
film and a second adhesive layer. A first side of the second
adhesive layer is connected to the supporting film, and a second
side of the second adhesive layer is adhered to a second surface of
the insulation film, wherein bonding strength of the second
adhesive film is smaller than bonding strength of the first
adhesive film.
Inventors: |
Wu; Hsiu-Chu; (KAOHSIUNG,
TW) ; Yu; Ching-Wen; (KAOHSIUNG, TW) ; Chen;
Wen-Chien; (KAOHSIUNG, TW) ; Su; Wu-Ying;
(KAOHSIUNG, TW) ; Huang; Wei-Yuan; (KAOHSIUNG,
TW) ; Tsai; Meng-Cheng; (KAOHSIUNG, TW) ;
Hung; Chi-Sheng; (KAOHSIUNG, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Taiflex Scientific Co., Ltd. |
Kaohsiung |
|
TW |
|
|
Family ID: |
56368523 |
Appl. No.: |
14/620197 |
Filed: |
February 12, 2015 |
Current U.S.
Class: |
428/41.8 ;
156/247; 428/212; 428/216 |
Current CPC
Class: |
H05K 2201/0154 20130101;
H05K 3/025 20130101; H05K 1/0393 20130101; H05K 3/007 20130101 |
International
Class: |
H05K 1/03 20060101
H05K001/03; H05K 3/46 20060101 H05K003/46 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 13, 2015 |
TW |
104101091 |
Claims
1. A cover film with high dimensional stability, comprising: an
insulation film; a first adhesive layer, a first side of the first
adhesive layer being connected to a first surface of the insulation
film, and a second side of the first adhesive layer being
configured to adhere to at least one metal conductor of a flexible
printed circuit board; and a carrier, comprising: a supporting
film; and a second adhesive layer, a first side of the second
adhesive layer being connected to the supporting film, and a second
side of the second adhesive layer being adhered to a second surface
of the insulation film; wherein bonding strength of the second
adhesive layer is smaller than bonding strength of the first
adhesive layer.
2. The cover film of claim 1, wherein the carrier is removable from
the second surface of the insulation film.
3. The cover film of claim 1, wherein thickness of the insulation
film is smaller than or equal to 12.5 .mu.m.
4. The cover film of claim 3, wherein thickness of the supporting
film is greater than or equal to 25 .mu.m.
5. The cover film of claim 1 further comprising a release film
covering on the second side of the first adhesive layer.
6. The cover film of claim 1, wherein the insulation film is made
of a material selected from a group consisting of a polyimide
resin, a polyester resin, a polyethylene terephthalate resin, a
polyethylene resin, a polypropylene resin, a polyvinyl chloride
resin, a polystyrene resin, and a polycarbonate resin.
7. The cover film of claim 1, wherein the supporting film is made
of a material selected from a group consisting of a polyimide
resin, a polyester resin, a polyethylene terephthalate resin, a
polyethylene resin, a polypropylene resin, a polyvinyl chloride
resin, a polystyrene resin, and a polycarbonate resin.
8. The cover film of claim 1, wherein the first adhesive layer is
formed by coating an acrylic acid resin, an epoxy resin, a phenol
formaldehyde resin or a polyester resin on the first surface of the
insulation film.
9. The cover film of claim 1, wherein the second adhesive layer is
formed by coating an acrylic acid resin, a polymerized siloxanes
resin, a rubber resin, an ethylene vinyl acetate (EVA) resin, a
polyurethane resin or a fluorine resin on the supporting film.
10. The cover film of claim 1, wherein dimensional stability of the
cover film is between -0.05% and 0.05%.
11. The cover film of claim 1, wherein bonding strength of the
first adhesive layer is between 0.4 kgf/cm and 2 kgf/cm, and
bonding strength of the second adhesive layer is between 5 gf/cm
and 100 gf/cm.
12. A manufacturing method of a flexible printed circuit board,
comprising: providing a cover film, wherein the cover film
comprises an insulation film, a first adhesive layer, and a
carrier, a first side of the first adhesive layer is connected to a
first surface of the insulation film, the carrier comprises a
supporting film and a second adhesive layer, a first side of the
second adhesive layer is connected to the supporting film, and a
second side of the second adhesive layer is adhered to a second
surface of the insulation film; adhering a second side of the first
adhesive layer to at least one metal conductor; and after adhering
the second side of the first adhesive layer to the at least one
metal conductor, removing the carrier from the second surface of
the insulation film.
13. The manufacturing method of claim 12, wherein the cover film
further comprises a release film covering on the second side of the
first adhesive layer, the method further comprises: removing the
release film before adhering the second side of the first adhesive
layer to the at least one metal conductor.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to a cover film with high
dimensional stability and a manufacturing method of flexible
printed circuit board, and more particularly, to a cover film with
high dimensional stability and a manufacturing method of flexible
printed circuit board capable of improving dimensional stability
and production efficiency.
[0003] 2. Description of the Prior Art
[0004] With the progress of related technology, thinner electronic
devices are developed according to demands. In order to reduce
thickness of an electronic device, internal electronic components
of the electronic device must also be thinner. The electronic
device usually comprises a flexible printed circuit board connected
to different electronic components for signal transmission.
Generally, the flexible printed circuit board is formed by adhering
an insulation film to metal wires. In order to reduce thickness of
the flexible printed circuit board, thickness of the insulation
film must also be decreased. However, when the thickness of the
insulation film of the flexible printed circuit board is decreased,
the insulation film may be easily deformed due to weakened
mechanical strength, so as to cause dimension error, which further
increases difficulty to align a positioning hole of the insulation
film to a positioning jig. Moreover, it is more difficult for
operators to precisely attach a thinner insulation film on the
metal wires, so as to decrease production efficiency and yield of
the flexible printed circuit board.
SUMMARY OF THE INVENTION
[0005] The present invention provides a cover film with high
dimensional stability and a manufacturing method of flexible
printed circuit board capable of improving dimensional stability
and production efficiency, in order to solve problems of the prior
art.
[0006] The cover film with high dimensional stability of the
present invention comprises an insulation film, a first adhesive
layer, and a carrier. A first side of the first adhesive layer is
connected to a first surface of the insulation film, and a second
side of the first adhesive layer is configured to adhere to at
least one metal conductor of a flexible printed circuit board. The
carrier comprises a supporting film and a second adhesive layer. A
first side of the second adhesive layer is connected to the
supporting film, and a second side of the second adhesive layer is
adhered to a second surface of the insulation film, wherein bonding
strength of the second adhesive film is smaller than bonding
strength of the first adhesive film.
[0007] In an embodiment of the present invention, the carrier is
removable from the second surface of the insulation film.
[0008] In an embodiment of the present invention, thickness of the
insulation film is smaller than or equal to 12.5 .mu.m.
[0009] In an embodiment of the present invention, thickness of the
supporting film is greater than or equal to 25 .mu.m.
[0010] In an embodiment of the present invention, the cover film
further comprises a release film covering on the second side of the
first adhesive layer.
[0011] In an embodiment of the present invention, the insulation
film is made of a material selected from a group consisting of a
polyimide resin, a polyester resin, a polyethylene terephthalate
resin, a polyethylene resin, a polypropylene resin, a polyvinyl
chloride resin, a polystyrene resin, and a polycarbonate resin.
[0012] In an embodiment of the present invention, the supporting
film is made of a material selected from a group consisting of a
polyimide resin, a polyester resin, a polyethylene terephthalate
resin, a polyethylene resin, a polypropylene resin, a polyvinyl
chloride resin, a polystyrene resin, and a polycarbonate resin.
[0013] In an embodiment of the present invention, the first
adhesive layer is formed by coating an acrylic acid resin, an epoxy
resin, a phenol formaldehyde resin or a polyester resin on the
first surface of the insulation film.
[0014] In an embodiment of the present invention, the second
adhesive layer is formed by coating an acrylic acid resin, a
polymerized siloxanes resin, a rubber resin, an ethylene vinyl
acetate (EVA) resin, a polyurethane resin or a fluorine resin on
the supporting film.
[0015] The manufacturing method of flexible printed circuit board
of the present invention comprises providing a cover film, wherein
the cover film comprises an insulation film, a first adhesive
layer, and a carrier, a first side of the first adhesive layer is
connected to a first surface of the insulation film, the carrier
comprises a supporting film and a second adhesive layer, a first
side of the second adhesive layer is connected to the supporting
film, and a second side of the second adhesive layer is adhered to
a second surface of the insulation film; adhering a second side of
the first adhesive layer to at least one metal conductor; and after
adhering the second side of the first adhesive layer to the at
least one metal conductor, removing the carrier from the second
surface of the insulation film.
[0016] In an embodiment of the present invention, the cover film
further comprises a release film covering on the second side of the
first adhesive layer, and the manufacturing method further
comprises removing the release film before adhering the second side
of the first adhesive layer to the at least one metal
conductor.
[0017] In contrast to the prior art, the cover film of the flexible
printed circuit board of the present invention comprises a carrier
to support the insulation film, in order to increase overall
mechanical strength. Therefore, dimensional stability of the
insulation film is improved to solve the deformation problem
induced by thinner thickness. Moreover, when manufacturing the
flexible printed circuit board, since the insulation film is
supported by the carrier, operators can hold the insulation film
steady to attach the insulation film to the metal conductor rapidly
and precisely. As a result, the cover film of the present invention
is capable of improving the production efficiency and yield rate of
the flexible printed circuit board.
[0018] These and other objectives of the present invention will no
doubt become obvious to those of ordinary skill in the art after
reading the following detailed description of the preferred
embodiment that is illustrated in the various figures and
drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] FIG. 1 is a diagram showing a cover film with high
dimensional stability of the present invention.
[0020] FIG. 2 is a diagram illustrating a manufacturing method of
the cover film with high dimensional stability of the present
invention.
[0021] FIG. 3 is a diagram illustrating a manufacturing method of a
flexible printed circuit board of the present invention.
[0022] FIG. 4 is a flowchart showing the manufacturing method of
the flexible printed circuit board of the present invention.
DETAILED DESCRIPTION
[0023] Please refer to FIG. 1. FIG. 1 is a diagram showing a cover
film with high dimensional stability of the present invention. As
shown in FIG. 1, the cover film 100 with high dimensional stability
of the present invention comprises an insulation film 110, a first
adhesive layer 120, and a carrier 130. The insulation film 110 can
be made of a material selected from a group consisting of a
polyimide resin, a polyester resin, a polyethylene terephthalate
resin, a polyethylene resin, a polypropylene resin, a polyvinyl
chloride resin, a polystyrene resin, and a polycarbonate resin. A
first side (upper side) of the first adhesive layer 120 is
connected to a first surface (lower surface) of the insulation film
110, and a second side (lower side) of the first adhesive layer 120
is configured to adhere to at least one metal conductor of a
flexible printed circuit board. The first adhesive layer 120 can be
formed by coating a material, which is selected from a group
consisting of an acrylic acid resin, an epoxy resin, a phenol
formaldehyde resin and a polyester resin, on the first surface of
the insulation film 110. The carrier 130 comprises a supporting
film 132 and a second adhesive layer 134. The supporting film 132
can be made of a material selected from a group consisting of a
polyimide resin, a polyester resin, a polyethylene terephthalate
resin, a polyethylene resin, a polypropylene resin, a polyvinyl
chloride resin, a polystyrene resin, and a polycarbonate resin. A
first side (upper side) of the second adhesive layer 134 is
connected to the supporting film 132, and a second side (lower
side) of the second adhesive layer 134 is adhered to a second
surface (upper surface) of the insulation film 110. The second
adhesive layer 134 can be formed by coating a material, which is
selected from a group consisting of an acrylic acid resin, a
polymerized siloxanes resin, a rubber resin, an ethylene vinyl
acetate (EVA) resin, a polyurethane resin and a fluorine resin, on
the supporting film 132. In order to allow the carrier 130 to be
removed from the second surface of the insulation film 110, bonding
strength of the second adhesive layer 134 is smaller than bonding
strength of the first adhesive layer 132. In an embodiment of the
present invention, the bonding strength of the first adhesive layer
132 is between 0.4 kgf/cm and 2 kgf/cm, the bonding strength of the
second adhesive layer 134 is between 5 gf/cm and 100 gf/cm, and
de-bonding strength of the second adhesive layer 134 is between 5
gf/5 cm and 100 gf/5 cm. For example, when the first adhesive layer
132 is made of the epoxy resin, actual measured bonding strength of
the first adhesive layer 132 is about 1 kgf/cm. When the second
adhesive layer 134 is made of the acrylic acid resin, actual
measured bonding strength of the second adhesive layer 134 before
heating is about 14 gf/cm, and actual measured bonding strength of
the second adhesive layer 134 after heating is about 37 gf/cm.
De-bonding strength of the second adhesive layer 134 after heating
is about 37 gf/5 cm.
[0024] In addition, the cover film 100 can further comprise a
release film 140 covering on the second side of the first adhesive
layer 120 to avoid adhesion of foreign materials on the second side
of the first adhesive layer 120 before attaching to at least one
metal conductor.
[0025] Please refer to FIG. 2 and FIG. 1. FIG. 2 is a diagram
illustrating a manufacturing method of the cover film with high
dimensional stability of the present invention. As shown in FIG. 2,
the second adhesive layer 134 can be formed by coating an adhesive
material on the supporting film 132. The insulation film 110 is
further attached to the second adhesive layer 134. Then, the first
adhesive layer 120 is formed by coating an adhesive material on the
insulation film 110. Finally, the release film 140 is attached to
the first adhesive layer 120 to form the cover film 100 with high
dimensional stability of the present invention.
[0026] According to the above arrangement, when a thickness of the
insulation film 110 is decreased, the supporting film 132 of the
carrier 130 can still support the insulation film 110 for
increasing overall mechanical strength. Therefore, when the
adhesive material is applied to the insulation film 110 for forming
the first adhesive layer 120, deformation of the insulation film
110 is decreased, in other words, dimensional stability of the
insulation film 110 is improved.
[0027] For example, in an embodiment of the present invention, the
supporting film 132 is made of the polyester resin with a thickness
of 50-.mu.m, and a 6-.mu.m thick adhesive material is then coated
on the supporting film 132 to form the second adhesive layer 134.
The insulation film 110 is made of the polyimide resin with a
thickness of 5-.mu.m. After attaching the second adhesive layer 134
on the insulation film 110, a 15-.mu.m thick adhesive material is
then coated on the insulation film 110 to form the first adhesive
layer 120. Finally, the release film 140 is then attached on the
first adhesive layer 120 to form the cover film 100 with high
dimensional stability of the present invention. According to Method
A of IPC-TM-650 Method 2.2.2, dimensional stability (rate of
deformation before and after removing the release film) of the
insulation film 110 of the cover film 100 along a coating direction
of the first adhesive layer 120 is 0.022%, and dimensional
stability (rate of deformation before and after removing the
release film) of the insulation film 110 of the cover film 100
perpendicular to the coating direction of the first adhesive layer
120 is 0.013%. Dimensional stability of the insulation film 110 of
the cover film 100 of the present invention meets the industrial
requirement within plus or minus 0.05%.
[0028] On the other hand, in a control group, the insulation film
is made of the polyimide resin with a thickness of 5-.mu.m, and
then directly coated with a 15-.mu.m thick adhesive material
without support of the carrier to form an adhesive layer. Finally,
a release film is attached to the adhesive layer to forma cover
film of the prior art. According to Method A of IPC-TM-650 Method
2.2.2, dimensional stability (rate of deformation before and after
removing the release film) of the insulation film of the cover film
of the prior art along a coating direction of the adhesive layer is
-0.185%, and dimensional stability (rate of deformation before and
after removing the release film) of the insulation film of the
cover film of the prior art perpendicular to the coating direction
of the adhesive layer is -0.018%. Dimensional stability of the
insulation film of the cover film of the prior art does not meet
the industrial requirement within plus or minus 0.05%.
[0029] In addition, the above embodiments of the present invention
are illustrated as examples, the insulation film 110, the
supporting film 132, the first adhesive film 120 and the second
adhesive film 134 are not limited to the thickness in the above
embodiments. In an embodiment of the present invention, the
thickness of the insulation film 110 is smaller than or equal to
12.5 .mu.m. The thickness of the supporting film 132 is greater
than or equal to 25 .mu.m. When the thickness of the insulation
film 110 is smaller than or equal to 12.5 .mu.m, the insulation
film 110 may easily deform, and the supporting film 132 can provide
relatively stable support to the insulation film 110, so as to
improve dimensional stability of the insulation film 110, and
further solve the problem of aligning a positioning hole of the
insulation film 110 to a positioning jig due to deformation. The
thickness of the first adhesive layer 120 is greater than or equal
to 10 .mu.m. The thickness of the second adhesive layer 134 is
greater than or equal to 1 .mu.m. When the first adhesive layer 120
and the second adhesive layer 134 are made of a same adhesive
material, the thickness of the second adhesive layer 134 is less
than thickness of the first adhesive layer 120 so that bonding
strength of the second adhesive layer 134 is smaller than bonding
strength of the first adhesive layer 132.
[0030] Please refer to FIG. 3. FIG. 3 is a diagram illustrating a
manufacturing method of a flexible printed circuit board of the
present invention. As shown in FIG. 3, when manufacturing a
flexible printed circuit board, the releasing film 140 of the cover
film 100 will be removed first. Then, the second side of the first
adhesive layer 120 is adhered to a metal conductor 200 (e.g. metal
wire) of the flexible printed circuit board. After the second side
of the first adhesive layer 120 is adhered to the metal conductor
200, the carrier 130 is removed from the second surface of the
insulation film 110. Moreover, the other side of the metal
conductor 200 can be attached with an insulation film to further
form a single layer or multilayer flexible printed circuit
board.
[0031] According to the above arrangement, since the supporting
film 132 of the carrier 130 can support the insulation film 110 to
increase overall mechanical strength, operators can hold the
insulation film 110 steady to attach the insulation film 110 to the
metal conductor 200 rapidly and precisely. As a result, the cover
film 100 of the present invention can improve production efficiency
and yield rate of the flexible printed circuit board.
[0032] Please refer to FIG. 4. FIG. 4 is a flowchart 400 showing
the manufacturing method of flexible printed circuit board of the
present invention. The flowchart of the manufacturing method of the
flexible printed circuit board of the present invention comprises
the following steps:
[0033] Step 410: Provide a cover film, wherein the cover film
comprises an insulation film, a first adhesive layer, and a
carrier, a first side of the first adhesive layer is connected to a
first surface of the insulation film, the carrier comprises a
supporting film and a second adhesive layer, a first side of the
second adhesive layer is connected to the supporting film, and a
second side of the second adhesive layer is adhered to a second
surface of the insulation film;
[0034] Step 420: Adhere a second side of the first adhesive layer
to at least one metal conductor; and
[0035] Step 430: After adhering the second side of the first
adhesive layer to the at least one metal conductor, remove the
carrier from the second surface of the insulation film.
[0036] In contrast to the prior art, the cover film of the flexible
printed circuit board of the present invention comprises a carrier
to support the insulation film, in order to increase overall
mechanical strength. Therefore, dimensional stability of the
insulation film is improved to solve the deformation problem
induced by thinner thickness. Moreover, when manufacturing the
flexible printed circuit board, since the insulation film is
supported by the carrier, operators can hold the insulation film
steady to attach the insulation film to the metal conductor rapidly
and precisely. As a result, the cover film of the present invention
is capable of improving the production efficiency and yield rate of
the flexible printed circuit board.
[0037] Those skilled in the art will readily observe that numerous
modifications and alterations of the device and method may be made
while retaining the teachings of the invention. Accordingly, the
above disclosure should be construed as limited only by the metes
and bounds of the appended claims.
* * * * *